William received his medical training at Trinity College, Dublin, qualifying M.B., B.Ch. in 1884. He took up a commission within the Medical Services at the rank of Surgeon Captain on 30th May 1885, then in 1895 served in Chitral. On 30th May 1897 he gained promotion to the rank of Major, and served in the N W Frontier, India from 1897 to 1898. From 1900 to 1902 he served in South Africa, being granted a local rank of Colonel whilst in charge of a general hospital there on 12th June 1900. On 30th May 1905 he was promoted to the rank of Lieutenant Colonel. William was stationed at Chester when war was declared. He was given the post of Assistant Director of Medical Services, 7th Division, and entered war in France on 7th October 1914. The following day he was promoted to the rank of Colonel. On 7th April 1915, he was transferred from the 7th Division to the 5th Division, where he took up the post of their A.D.M.S. until 13th July 1915 when he received a wire with orders that he was to be Deputy Director of Medical Services, 7th Corps, and that he was to report to the A.G. at G.H.Q. the following morning. In 1915 he was granted companion Order of the Bath (Military). In January 1918, now serving under the rank of Major General, William arrived in Egypt to replace Surgeon General Maher, taking up the post of Director of Medial Services, General Headquarters, Egypt.